Modular implantable medical pump

ABSTRACT

An implantable medical pump system can include a blood pump comprising a pump housing defining a passage therethrough and a rotor within the passage. The blood pump further includes one or more elements at least partially contained within the housing adapted to actuate the rotor to drive fluid though the passage. The pump housing includes at least one coupling feature. The system further includes an inflow cannula defining a lumen therethrough. The inflow cannula is adapted to be mechanically coupled to the at least one coupling feature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the full benefit of U.S.Provisional Patent Application No. 61/606,767, filed Mar. 5, 2012 andtitled “Modular Implantable Medical Pump,” which is incorporated hereinby reference in its entirety for all purposes.

TECHNICAL FIELD

This document relates to modular implantable medical pumps, such asventricular assist blood pumps. This document also describes a method ofcalibrating implantable medical pumps.

BACKGROUND

The human heart is a complex and critical pump. Various pathologies canmake the heart become dysfunctional, acutely or chronically. Heartfailure can be treated with pharmacologic therapy and/or hearttransplantation. Mechanical assistance is another therapeutic option forheart failure. For example, an afflicted person waiting to receive atransplant may receive mechanical assistance until a donor heart isavailable.

Blood pumps are commonly used to provide mechanical assistance oraugmentation to the pumping performed by the left and/or rightventricles of the heart. For example, an implantable pump can beconnected in parallel with the person's heart and implanted adjacent tothe heart, in contact with the heart, or in a remote location such asthe abdomen and inside or outside of the thoracic cavity in the chestarea. A blood pump supplementing a ventricle is known as a ventricularassist device, or VAD. A VAD is useful when the ventricle alone cannotprovide adequate blood flow. A pump can also completely replace thefunction of a ventricle.

SUMMARY

In a general aspect, a blood pump includes a coupling interface tocouple to any of a plurality of different inflow cannulas.

In another general aspect, a blood pump includes a coupling interface tocouple to any of a plurality of different pump covers that define anoutflow port. The different pump covers can each define a volute for theblood pump.

In another general aspect, a blood pump comprises a motor housing and apump cover that defines an outlet. The pump cover is rotatable relativeto the motor housing to change a position of the outlet relative to thepump cover.

In another general aspect, a blood pump defines a blood flow path andincludes textured surfaces that promote growth of a biologic layer onsurfaces in the blood flow path. In some implementations, the texturedsurfaces are included only on components that are removable from a pumphousing that includes the motor of the pump.

In another general aspect, a method of calibrating a blood pump includescoupling to the blood pump a calibration component that hassubstantially equivalent characteristics to a pump component that has atextured surface. In some implementations, the calibration component hasa smooth surface in the region where the pump component has the texturedsurface. In some implementations, the calibration component has atextured surface in the region where the pump component has the texturedsurface.

In another general aspect, an implantable medical pump system includes ablood pump including a pump housing defining a passage therethrough anda rotor within the passage. The blood pump further includes one or moreelements at least partially contained within the pump housing adapted toactuate the rotor to drive fluid though the passage. The pump housingincludes at least one coupling feature. The system further includes aninflow cannula defining a lumen therethrough. The inflow cannula isadapted to be mechanically coupled to the at least one coupling feature.

Implementations may include one or more of the following features. Forexample, at least a portion of the inflow cannula extends into thepassage when the inflow cannula is attached to the at least one couplingfeature. The inflow cannula includes a textured blood-contactingsurface. The textured blood-contacting surface includes sinteredtitanium powder. The textured surface is disposed on at least a portionof an outer diameter of the inflow cannula and at least a portion of aninner diameter of the inflow cannula. Substantially all of theblood-contacting surfaces of the inflow cannula include a texturedcoating. The inflow cannula is adapted to extend out from the pumphousing when coupled to the at least one coupling feature such that aportion of the inflow cannula is adapted to traverse the myocardium ofthe heart. The inflow cannula includes: a first portion having a lengthsufficient to traverse a heart wall, the lumen extending through thefirst portion; an exterior thread pattern to mate with an interiorthread pattern of the blood pump, the first portion protruding from theblood pump when the exterior thread pattern engages the interior threadpattern of the blood pump; and a second portion having a generallycylindrical outer surface received inside the passage of the blood pumpwhen the exterior thread pattern engages the interior thread pattern ofthe blood pump, the second portion having a smaller outer diameter thanthe first portion. The inflow cannula is adapted to extend along atleast 50% of the length of the passage when mechanically coupled to theat least one coupling feature. The passage defines a rotor well thatreceives the rotor, and the inflow cannula is adapted to extend to therotor well when mechanically coupled to the at least one couplingfeature. The system includes multiple inflow cannulas each adapted to bereversibly mechanically coupled to the at least one coupling featuresuch that at least a portion of the flow cannula extends into thepassage, at least two of the inflow cannulas having different lengths.At least a first inflow cannula is adapted for traversing the myocardiumof a left ventricle and a second inflow cannula is adapted fortraversing the myocardium of a right ventricle. The system furtherincludes a mounting cuff adapted to mechanically couple the pump housingto the myocardium of a heart, the mounting cuff comprising an innersurface adapted to fit around an outer perimeter of the inflow cannulaor the pump housing. The system further includes a pump cover adapted tobe mechanically coupled to the pump housing, the pump cover comprising atextured blood-contacting surface. The system further includes a pumpcover adapted to be mechanically coupled to the pump housing, and thepump cover is free of textured blood-contacting surfaces. The at leastone coupling feature includes a thread and the inflow cannula includes acorresponding thread. The system further includes one or more tools toconnect the inflow cannula to the pump housing with a predeterminedamount of torque. The at least one coupling feature and the inflowcannula comprise corresponding snap and mating surfaces. The lumen istapered.

In another general aspect, a method of calibrating an implantablemedical pump includes attaching a blood pump to a calibration cannulathat approximates an inflow cannula for the blood pump. The method mayinclude attaching the blood pump to a calibration cover thatapproximates a pump cover for the blood pump. The calibration cannulaand calibration cover have smooth surfaces corresponding to the regionswhere the inflow cannula and pump cover have textured surfaces. Theblood pump includes a pump housing defining a passage therethrough and arotor within the passage. The pump housing at least partially containsone or more elements adapted to actuate the rotor to drive fluid throughthe passage. The method includes operating the blood pump in acalibration fluid while the motor is attached to the calibrationcannula, and recording calibration variables based on a flow, apressure, a speed, an operational power, or a combination thereof of thecalibration fluid pumped by the blood pump. The method includesdetaching the blood pump from the calibration cannula after operatingthe blood pump in the calibration fluid.

Implementations may include one or more of the following features. Forexample, the method further includes storing the recorded calibrationvariables in a memory associated with the implantable medical pump. Themethod further includes cleaning the blood pump after operating theblood pump in the calibration fluid. The method further includesattaching the inflow cannula to the blood pump motor after detaching thecalibration cannula. Attaching the blood pump to the calibration cannulathat approximates the inflow cannula for the blood pump includesattaching to the blood pump a calibration cannula that has a smooth ortextured inner surface that defines a lumen, the inflow cannula having atextured surface that defines a lumen, the textured surface that definesthe lumen of the inflow cannula comprising a powdered metal coating. Thelumen of the calibration cannula and the lumen of the inflow cannulahave dimensions that are substantially equal or are produced by the samemanufacturing process. The method further includes attaching acalibration cover to the pump housing prior to operating the blood pumpin the calibration fluid, the calibration cover approximating a pumpcover for the blood pump and having a smooth or textured surfacecorresponding to a region where the pump cover has a textured surface.The calibration cover and the pump cover each define a volute, thecalibration cover has a smooth or textured surface that defines thevolute of the calibration cover, and the pump cover has a texturedsurface that defines the volute of the pump cover, the textured surfacethat defines the volute of the pump cover comprising a powdered metalcoating. The volute of the calibration cover and the volute of the pumpcover have dimensions that are substantially equal. The method furtherincludes detaching the calibration cover from the pump housing afteroperating the blood pump in the calibration fluid. The method furtherincludes attaching the pump cover to the pump housing after detachingthe calibration cover. The blood pump defines a blood flow path, and thepump housing does not include any surfaces having a powdered metalcoating in the blood flow path. The blood pump is packaged with one ormore inflow cannulas. The one or more inflow cannulas each comprise: afirst portion having a length sufficient to traverse a heart wall; anexterior thread pattern to mate with an interior thread pattern of theblood pump, the first portion protruding from the blood pump when theexterior thread pattern engages the interior thread pattern of the bloodpump; and a second portion having a generally cylindrical outer surfacereceived inside the passage of the blood pump when the exterior threadpattern engages the interior thread pattern of the blood pump, thesecond portion having a smaller outer diameter than the first portion.The blood pump may be packaged with one or more tools for attaching theone or more inflow cannulas to the motor. The blood pump may beassembled with a particular inflow cannula at the manufacturingfacility. The pump housing includes smooth surfaces. The pump housingdoes not include any textured surfaces that promote tissue deposition.The textured surface of the inflow cannula or the pump cover includes asurface formed of a sintered titanium powder.

In another general aspect, a blood-pump inflow cannula includes a firstportion having a length sufficient to traverse a heart wall. The inflowcannula also includes an exterior thread pattern along an exteriorsurface of the blood-pump inflow cannula to mate with an interior threadpattern of a passage of a blood pump, the first portion protruding fromthe blood pump when the exterior thread pattern engages the interiorthread pattern of the blood pump. The inflow cannula includes a secondportion opposite the first portion having a generally cylindrical outersurface received inside the passage of the blood pump when the exteriorthread pattern engages the interior thread pattern of the blood pump,the second portion having a smaller outer diameter than the firstportion. The blood-pump inflow cannula defines a lumen extending throughthe first portion and the second portion.

Implementations may include one or more of the following features. Forexample, the first portion has a tapered inner diameter. An outersurface of the second portion includes grooves. The outer surface of thesecond portion includes a ridge. The ridge includes grooves. The inflowcannula may be packaged separately from a blood pump or assembled at themanufacturing facility.

In another general aspect, a blood-pump-inflow-cannula attachment socketincludes a body defining a cavity having a cylindrical inside surface,the cylindrical inside surface generally corresponding to an outersurface of a blood-pump inflow cannula, the body further comprising aplurality of grooves or projections that interlock with correspondingridges, grooves, or notches of a blood-pump inflow cannula.

In some implementations, the body includes projections extending from arim of the cavity and corresponding to notches in a ridge of ablood-pump inflow cannula.

In another general aspect, a wrench system includes theblood-pump-inflow-cannula attachment socket described above. In someimplementations, the wrench in the wrench system is a torque-limitingwrench or a torque-measuring wrench.

In another general aspect, an implantable medical pump system includes ablood pump comprising a pump housing defining a passage therethrough anda rotor within the passage. The pump housing at least partially containsone or more elements adapted to actuate the rotor to drive fluid throughthe passage, and the pump housing includes at least one threadedelement. The implantable medical pump system includes an inflow cannuladefining a lumen therethrough, and the inflow cannula has a threadedexterior adapted to mate with the at least one threaded element.

Implementations may include one or more of the following features. Forexample, the at least one threaded element defines a lower surface ofthe pump housing. At least one threaded element is adapted to rotatewith respect to a remainder of the pump housing given a sufficienttorque application. At least one threaded element is held against theremainder of the pump housing by a capture ring. At least one threadedelement includes one or more grooves, notches, or ridges. One or moregrooves, notches, or ridges have a surface oriented generally in a planeincluding an axis of the threads. At least a portion of the inflowcannula extends into the passage when the inflow cannula is attached tothe at least one coupling feature. The inflow cannula includes atextured blood-contacting surface. The textured blood-contacting surfaceincludes sintered titanium powder.

In another general aspect, an implantable medical pump system includes apump housing defining a passage therethrough and a rotor at leastpartially disposed in the passage. The pump housing at least partiallycontains one or more elements configured to actuate the rotor to drivefluid through the passage. The implantable medical pump system includesan inflow cannula that is removably attachable to the pump housing. Theinflow cannula has an inner surface that defines a lumen through theinflow cannula, and the inner surface of the lumen has a texturedblood-contacting surface. The implantable medical pump system includes apump cover that is removably attachable to the pump housing. The pumpcover has an inner surface that defines a volute, and the inner surfaceof the pump cover has a textured blood-contacting surface.

In various embodiments, one or more of the blood-contacting surfaces istextured.

The textured surfaces may be made from a metal, such as a powderedmetal, or a polymer. In various embodiments, the textured surface is asintered titanium beaded surface. In various embodiments, the roughnessof the textured surface is measured by determining a Ra value, and theRa value of the textured surface is greater than 100 millionths of aninch, greater than 200 millionths of an inch, or greater than 500millionths of an inch. In some embodiments, the textured surface has aRa value of at least 200 millionths of an inch, at least 500 millionthsof an inch, or at least 1000 millionths of an inch. In some embodiments,the textured surface has a Ra value of less than 10,000 millionths of aninch, less than 5,000 millionths of an inch, less than 1,000 millionthsof an inch, or less than 500 millionths of an inch. In some embodiments,the smooth surfaces can have a Ra value of less than 100 millionths ofan inch. The pump cover may also include textured blood-contactingsurfaces. The one or more of the blood-contacting surfaces may bemodified or treated in other manner. For example, the blood-contactingsurfaces may comprise a porous coating or relatively hard coating.

Implementations may include one or more of the following features. Forexample, the lumen extends into the passage when the inflow cannula isattached to the pump housing. The textured blood-contacting surfacescomprise a powdered metal coating, and the pump housing does not haveany blood-contacting surfaces that comprise a powdered metal coating.The powdered metal coating may include a sintered titanium coating. Theinflow cannula, the pump housing, and the pump cover define a blood flowpath through the pump, and the pump housing defines a rotor well thatreceives a portion of the rotor; and textured blood-contacting surfacesare disposed along the entire blood flow path except the rotor well. Atextured surface is disposed on at least a portion of an outer surfaceof the inflow cannula and at least a portion of an inner surface of theinflow cannula. The textured surface is disposed on at least a portionof an outer diameter of the inflow cannula and at least a portion of aninner diameter of the inflow cannula. Substantially all of theblood-contacting surfaces of the inflow cannula include a texturedcoating. The inflow cannula is dimensioned to extend along at least 50%of the length of the passage when the inflow cannula is received in thepassage. The passage defines a rotor well that receives the rotor, andthe inflow cannula is adapted to extend to the rotor well whenmechanically coupled to the at least one coupling feature.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

DESCRIPTION OF DRAWINGS

FIG. 1A is a perspective view of an exemplary implantable medical pump.

FIG. 1B illustrates an example of how an implantable medical pump can besecured to a heart.

FIG. 1C illustrates an overall system including the implantable medicalpump of FIG. 1B.

FIGS. 2A-2C are various cutaway views of the exemplary implantablemedical pump shown in FIG. 1A.

FIGS. 2D-2J are various cutaway and/or perspective views of pump coversaccording to a particular embodiment.

FIGS. 3A-3B illustrate an embodiment of an implantable medical pumphaving a single threaded attachment between the pump housing and theinflow cannula. FIG. 3A is a cross-sectional view of an implantablemedical pump having an inflow cannula according to a second embodiment.FIG. 3B is an expanded perspective view of the implantable medical pumpsystem showing how the inflow cannula of FIG. 3A is attached to the pumphousing.

FIGS. 4A and 4B illustrate a second embodiment of an implantable medicalpump system having a single threaded attachment between the pump housingand the inflow cannula. FIG. 4A is a cross-sectional view of depicting asingle threaded attachment between the pump housing and the inflowcannula. FIG. 4B is an expanded perspective view showing how the inflowcannula is attached to the pump housing.

FIGS. 5A and 5B illustrate an embodiment of an implantable medical pumpsystem having an inflow cannula having a multi-component threadedattachment. FIG. 5A is a cross-sectional view of depicting amulti-component threaded attachment between the pump housing and theinflow cannula. FIG. 5B is an expanded perspective view showing thearrangement of the components of this attachment feature.

FIGS. 6A and 6B illustrate a second embodiment of an implantable medicalpump system having an inflow cannula having a multi-component threadedattachment. FIG. 6A is a cross-sectional view of depicting amulti-component threaded attachment between the pump housing and theinflow cannula. FIG. 6B is an expanded perspective view showing thearrangement of the components of this attachment feature.

FIG. 7 illustrates an embodiment of an implantable medical pump systemhaving welded connection between an inflow cannula and the pump housing.

FIG. 8A is a perspective view of a blood pump having textured surfaces.FIGS. 8B and 8C illustrate an inflow cannula of the blood pump of FIG.8A, and FIGS. 8D to 8F illustrate a pump cover of the blood pump of FIG.8A.

FIG. 9 is a flow chart of a calibration process according to certainembodiments.

FIGS. 10A-10G illustrate a tool being used to secure an inflow cannulato a pump housing.

FIGS. 10H to 10M illustrate an adjustable pump cover of the implantablemedical pump of FIG. 1A.

DETAILED DESCRIPTION

FIG. 1A illustrates an example of an implantable medical pump system 100having a modular design that includes an inflow cannula 120 that can beseparated and reattached to a pump housing 110 of a blood pump 105.Moreover, a plurality of inflow cannulas 120 having different featurescan each be adapted for modular attachment to the pump housing 110 toadapt the implantable medical pump system 100 for a particular use. Forexample, some inflow cannulas can be adapted to assist the leftventricle, as illustrated in FIG. 1B, while other inflow cannulas can beadapted to assist the right ventricle.

Different patients can have heart-wall thicknesses that differ. Thesedifferences may not be apparent until the time of implantation.Moreover, a cannulation location for a particular patient may not becomeapparent until the time of implantation. Different chambers of the heartcan have varying flow pattern, which can also impact the type of inflowcannula used for a given implantation site. Different inflow cannulascan thus have different materials or coating, can have differentdiameters, can have different lengths, and/or can extend from themotor's base at different angles, such that each inflow cannula isadapted for a particular use and/or patient. Modular attachment of theinflow cannula 120 to the blood pump 105, whether by having a threadedconnection, a snap-fit connection, a welded connection, etc., can permita clinician to adapt a blood pump for a particular use.

The inflow cannula 120 can include a blood-and-tissue-compatibletextured surface 870 (shown in FIGS. 8A through 8F) and can extend intoa passage (e.g., 214 shown in FIG. 2A) defined in the pump housing 110.The blood-and-tissue-compatible textured surface 870 can encourage orpromote the formation and adherence of a biologic lining. In someembodiments, the inflow cannula 120 is adapted to extend into at leastfifty percent of the passage 214 of the pump housing 110 whenmechanically secured to the pump housing 110. For example, the inflowcannula 120 can extend inward past the electronics of the blood pump(e.g., stator, control electronics, PCB). In certain embodiments, theinflow cannula is adapted to extend to a rotor well 252 (shown in FIG.2A) that contains a rotor 255 (shown in FIG. 2A).

The blood pump 105 can be calibrated prior to use in order to ensurethat the blood pump is accurately controlled and provides appropriateflow estimations to the clinician when implanted. Each blood pump 105that is manufactured can be individually calibrated. In someimplementations, the blood pump 105 is calibrated using a calibrationcannula and/or a calibration cover different from the inflow cannula 120and/or the pump cover 160 that are actually implanted with the bloodpump 105. Using a different cannula or cover for calibration avoids theneed to clean (e.g., sterilize) the inflow cannula 120 and/or the pumpcover 160 as a result of calibration. In some instances, cleaning (e.g.,sterilizing) a textured surface, such as the textured surface 670 ofFIGS. 6A and 6B, after use in calibration may be difficult or timeconsuming. For example, during the calibration process, texturedsurfaces may collect contaminants that are difficult to dislodge.Because the pump housing 110 permits modular attachment of differentinflow cannulas and pump covers, the blood pump 105 may be calibratedwith a calibration cannula and/or calibration cover having smoothsurfaces, which are easier to clean than textured surfaces. The bloodpump 105 is then implanted with the inflow cannula 120 and/or the pumpcover 160 having textured surfaces.

A pre-implantation calibration method can include attaching the pumphousing 110 to a calibration cannula (not shown) and/or a calibrationcover (not shown), operating the blood pump in the calibration fluid,separating the calibration cannula and/or the calibration cover from thepump housing 110, and cleaning (e.g., sterilizing) the pump housing 110.The calibration cannula can have the same structure (e.g., the samedimensions) as the inflow cannula 220 shown in FIGS. 2A-2C, but in oneor more regions, the calibration cannula can have a surface texture thatis different from the surface texture of the inflow cannula 220. Forexample, the interior and/or exterior of the calibration cannula can besmooth surfaces, and the interior and/or exterior of the inflow cannula220 can be textured surfaces. The calibration cover can have the samestructure (e.g., the same dimensions) as the pump cover 260 shown inFIGS. 2D-2J, but in one or more regions, the calibration cover can havea surface texture that is different from the surface texture of the pumpcover 260. For example, the interior of the calibration cover thatdefines a volute can have smooth surfaces, and the interior of the pumpcover 260 that defines a volute can have textured surfaces.

The calibration cannula and/or calibration cover can affect liquid flowrates in substantially the same manner as the inflow cannula 120 and/orthe pump cover 160. Operation of the blood pump 105 with the calibrationcomponents can be within a predetermined acceptable tolerance ofoperation of the blood pump 105 with clinical components. For example,performance of the blood pump 105 with the calibration components havingsmooth surfaces may be within 20% or less, 10% or less, or 5% or less ofthe performance of the blood pump 105 with clinical components havingtextured surfaces.

The use of the calibration cannula and/or calibration cover can avoidexposing surfaces having a geometry that might capture contamination tosources of contamination from the calibration procedure. After thecalibration, the pump housing 110 can be attached to the pump cover 160and/or the inflow cannula 120. The pump cover 160 and/or inflow cannula120 can be of clinical grade, but may also be nearly identical to thecalibration cannula and/or calibration cover.

As noted above, a textured surface, can present a contamination risk dueto the added difficulty of cleaning a textured surface as compared tocleaning a smooth surface. The modular design of the blood pump 105,however, can reduce the contamination risk caused by pre-implantationcalibration methods. For example, the inflow cannula 120 of the modularblood-pump system provides a textured surface extending into the pumphousing 110, thus minimizing smooth surfaces exposed to blood when theblood pump 105 is implanted. Use of a calibration cannula having asmooth interior surface instead of a textured surface during calibrationreduces a contamination risk associated with pre-implantationcalibration procedures. An example of a pre-implantation calibrationmethod is discussed in further detail below in reference to FIG. 9.

The implantable medical pump system can be provided as a kit including ablood pump 105 (including a pump housing 110) and one or more inflowcannulas. The kit can further include one or more pump covers 160 asseparate components. In some embodiments, the kit can include one ormore tools configured to help a clinician connect the inflow cannulaand/or pump cover to the pump housing 110. For example, a connectionsocket 1000 and torque wrench 1010 are described below in reference toFIGS. 10A-10G.

A system and/or kit including a plurality of inflow cannulas and/or pumpcovers (and optionally one or more tools to attach the inflow cannulasand/or pump covers) permits a clinician to make a determination of theparticular implantation site and the type of cannula or cannula positionduring the implantation procedure once the clinician is observing thepatient's anatomy. One or more tools can ensure that the selected inflowcannula and/or pump cover is connected appropriately (e.g., with adesired amount of torque). The tool(s) and/or inflow cannulas and/orpump covers adapted for attachment to a pump housing 110 can also besold separately and/or held in stock by a hospital or clinician.

In some implementations, the system or kit can include a component thatcan be rotated to change the position of an outflow port 165 relative tothe pump housing 110 given a predetermined amount of torque application.For example, the pump cover 160 may define the outflow port 165 for theblood pump 105. The pump cover 160 can be rotated relative to the pumphousing 110 to alter the position of the outflow port 165 with respectto the pump housing 110. In some implementations, the pump cover 160 canbe replaced with a different cover having an outflow port with adifferent trajectory.

Rotation of the pump cover 160 or replacement of the pump cover 160 canpermit a clinician to position the outflow port for various implantationpositions, implantation techniques, and clinical applications. Forexample, the clinician may rotate the outflow conduit between a firstposition for use of the implantable medical pump 100 as a leftventricular assist device (LVAD), a second position for use as a rightventricular assist device (RVAD), and/or a third position for use in abiventricular assist device (BiVAD) configuration. Other positions maybe used for, for example, ascending aorta anastomosis, descending aortaanastomosis, and other implantation configurations. Similarly, theposition of outflow port 165 may be adjusted to accommodate implantationat the apex of the left ventricle (e.g., with an apical approach), orwith the pump housing 110 spaced apart from the myocardial wall of theheart.

Implantable Medical Pump Assembly

The implantable medical pump assembly 100 can be a ventricular assistdevice (VAD). A VAD is a mechanical circulatory device that is used topartially or completely replace the function of a failing heart. SomeVADs are intended for short term use, for patients recovering from heartattacks or heart surgery, while others are intended for long term use(e.g., months, years, or the remainder of a patient's life). VADS areoften used for patients suffering from heart failure. VADs are designedto assist either the right (RVAD) or left (LVAD) ventricle, or both atonce (BiVAD). Some assist devices are cannulated to the atria instead ofthe ventricles.

Referring to FIGS. 1A-1C and 2A-2C, the modular implantable medical pumpassembly 100 can include a blood pump 105 having a pump housing 110 thatdefines a rotor well 252 (shown in FIGS. 2A-2C) that receives at least aportion of a rotor 255. The pump housing 110 also houses elements 290(e.g., control electronics, stators, stator coils, electrical hardware)designed to actuate the rotor 255 to pump blood though a passage 214.The blood pump 105 can have a generally cylindrical shape. Inflowcannula 120 projects out of the blood pump 105 so that it may extendinto a chamber of the heart, as shown in FIG. 1B. The selection ofdifferent inflow cannulas can permit the placement of the modularimplantable medical pump assembly 100 at different locations. A heartcontacting surface of the pump housing 110 can include a pump cap 230.The blood pump 105 also includes an outflow port 165 for expelling bloodthat has been drawn by the blood pump 105 from the interior chamber ofthe heart.

FIGS. 2A-2C illustrate an embodiment of an implantable medical pump 200having a pump housing 210 defining a flow passage 214 therethrough andcontaining elements 290 (e.g., stator coils) adapted to drive the rotor255 contained in a rotor well 252 of the flow passage 214. The pumphousing 210 includes a pump cap 230 having a generally flat base. Thepump cap 230 can have a generally cylindrical perimeter. The pump cap230 can additionally include attachment features 232 that secure thepump housing 210 to an apical attachment cuff. The exemplary apicalattachment cuff is an assembly that a clinician can attach to themyocardium to provide a method for attaching the implantable medicalpump 200 to a heart. The apical attachment cuff can also providing ahemostatic seal. Apical attachment cuff are discussed in further detailin provisional patent application number 61/448,434, which is herebyincorporated by reference in its entirety. In some implementations, theapical attachment cuff fits over the inflow cannula 220 and engagesexterior features of the inflow cannula 220 to couple to the implantablemedical pump 200. A locking mechanism, such as a clip or other fastenercan further secure the apical attachment cuff to the implantable medicalpump 200.

The pump cap 230 can also include a coupling feature 212 for securing aninflow cannula 220 to the pump housing 210. In some embodiments, theapical attachment cuff 232 and the coupling feature 212 are machinedinto the pump cap 230 and/or the pump housing 210. In other embodiments,the coupling feature 212 is welded to the pump cap 230 and/or the pumphousing 210.

The inflow cannula 220 is adapted to be connected to the couplingfeature 212 of the pump housing 210 by a corresponding coupling feature222. In the embodiments shown, the coupling feature 222 includes threadscorresponding to threads in coupling feature 212. The inflow cannula isthreaded into the pump housing 210 until the end of the inflow cannula220 is seated in or against an opening of the rotor well 252. In theembodiment shown, the threaded attachment feature protrudes out from thepump housing 210 along a periphery of a flow passage 214 through thepump housing 210. This simple-thread coupling feature 212 featured inFIGS. 2A and 2B includes only a single leak pathway. The threadedconnection may be designed such that a predetermined amount of torquecan be used to secure the inflow cannula 220 to the pump housing 210 andthus mitigate the risk of auto rotation of the inflow cannula duringuse. In other embodiments, the coupling feature can be a snap-fitcoupling feature. In addition to reversible coupling features, permanentcoupling features are also contemplated (see FIG. 7 discussed below).For example, anchors can be positioned on the pump cap 230 and/or theinflow cannula 220 to stop back rotation. Moreover, one or more couplingfeatures can be located within the flow passage 214. For example, thethreaded connection can be along the flow passage 214.

At least a portion of the inflow cannula 220 extends into the flowpassage 214. As shown, a first end 224 of the inflow cannula 220 extendsinto the flow passage 214 to rotor well 252. In some embodiments, theinflow cannula 220 extends along at least fifty percent of the length ofthe flow passage 214 when the inflow cannula is connected to thecoupling feature 212.

The inflow cannula 220 defines a lumen 228 through which blood cantravel when the implantable medical pump 100 is implanted and inoperation. As discussed in detail below, particularly with regard toFIGS. 8A to 8F, the blood-contacting surfaces of the inflow cannula 220can have a blood-and-tissue-compatible textured surface. Ablood-and-tissue-compatible textured surface on the inside surface ofthe lumen 228 can thus extend into the flow passage 214 of the pumphousing. As depicted in FIG. 2A, the lumen 228 can be tapered towardsthe pump housing 210. A tapered lumen can minimize flow disruptions(e.g., turbulence, swirl). In some embodiments, the lumen includes agradual taper, which can be used to reduce the lumen opening to theappropriate diameter of the rotor and avoid a large pressure drops inthe system that may affect pump efficiency. Moreover, a larger openingat the mouth of the lumen, which is placed within the cardiac chamber,can help prevent stenosis or occlusion as a result of the typicalhealing response to the injury created during implantation or due toinflow cannula malposition following implantation.

The inflow cannula can include a ridge 229 around its outer perimeter. Aseal ring 217 can also be positioned between the ridge 229 and the pumpcap 230. The ridge 229 can press the seal ring 217 between the inflowcannula 220 and the pump cap 230. A seal ring 217 can mitigate the riskof bodily fluids passing into the pump housing 210 through athread/connection gap between the inflow and the housing.

The implantable medical pump 200 can also include a pump cover 260.FIGS. 2C-2J illustrate the pump cover 260 in greater detail, includingvarious cutaway views of the pump cover 260. The pump cover 260 definesan outflow port 265, which can be located along the perimeter of theimplantable medical pump 200. The pump cover 260 defines a volute 267,which is an interior volume in fluid communication with the outlet port265. In some implementations, the volute 267 has a cross sectionalvolume that expands in a circumferential direction about the axis ofrotation of the rotor 255. The volute 267 can convert kinetic energy ofblood flow in the volute 267 to pressure at the outlet port 265. Therotor 255 has blades 256 that extend into the volute 267. The rotor 255also defines a central opening 250 that admits blood through the rotor255 into the volute 267.

Blood-contacting surfaces of the pump cover 260 can includeblood-and-tissue-compatible textured surfaces, such as those discussedbelow with regard to the inflow cannula. As will be described furtherbelow, the blood-contacting pump components may include a texturedsurface, a smooth surface, or a combination thereof. The pump cover 260can be secured to the pump housing 210 by a reversible coupling feature,such as corresponding threads 242 and 262. As shown in FIGS. 2A and 2B,the pump system can include an O-ring 269 that is secured to the pumphousing 110 by threads 242 and 262 and holds a lip 268 of the pump cover260 against the pump housing 210. The outflow port 265 can expel bloodthat has been drawn by the implantable medical pump 200 from theinterior chamber of the heart and accelerated by the rotor 255 in therotor well 252.

The coupling feature that secures the pump cover 260 to the pump housing210 permits the pump cover 260 to be secured at any of multiplerotational orientations of the pump cover 260 with respect to the pumphousing 210. In some implementations, the coupling feature can securethe pump cover 260 at any rotational position with respect to the pumphousing 210, for example, at any incremental rotational position. Thecoupling feature may permit the pump cover 260 to be rotated relative tothe pump housing while the pump cover is secured to the pump housing 210with application of at least a predetermined amount of torque.

Because the pump cover 260 includes the outflow port 265, rotating thepump cover 260 relative to the pump housing 210 changes the position ofthe outflow port 265 relative to the pump housing 210. As shown, thepump cover 260 defines the entire volute 267. With the volute 267entirely contained in the pump cover 260, the pump implantable medicalpump 200 can produce the same flow characteristics with the pump cover260 in any of various rotational orientations with respect to the pumphousing 210.

The outflow port 265 can be fluidly connected via flexible conduit 167(see FIG. 1C) to the aorta or another anatomical feature such that blooddrawn from the heart can be expelled under pressure into the circulatorysystem of the user. In some implementations, the flexible conduit 167can be rotated, bent, twisted, or otherwise oriented with respect to theblood pump 105 while the flexible conduit 167 is secured to the bloodpump 105. As a result, the flexible conduit 167 accommodatesimplantation of the blood pump 105 at various positions relative to theheart 20.

FIGS. 3A and 3B depict an implantable medical pump 300 according to asecond embodiment having a similar construction to that of theembodiment of FIGS. 2A-2J. FIGS. 3A and 3B depict an inflow cannula 320having a discontinuous ridge 329 around its outer perimeter. The grooves327 in the discontinuous ridge 329 can permit a tool to easily grasp theinflow cannula for installing the inflow cannula to the pump housing310. An example of such a tool is that shown in FIGS. 10A-10G, discussedbelow. The pump cap 330 can be machined with the threaded couplingfeature 312 and/or the apical attachment cuff 332. The inflow cannula320 can be threaded into the coupling feature 312 until one end of theinflow cannula 320 is positioned in the flow passage 314 and seated inor against an opening of the rotor well 350. The threaded connectionbetween the inflow cannula 320 and the coupling feature 312 can be asingle threaded connection. The threads of the inflow cannula 320 andthe coupling feature 312 can be complementary so as to ensure a snugfit. A pump cover (not shown) can be secured to the pump housing viaattachment feature 342.

FIGS. 4A and 4B depict another embodiment of a blood pump system 400having a similar construction to that of the embodiments of FIGS. 2A-2Fand 3A-3B. FIGS. 4A and 4B also include a threaded attachment betweenthe inflow cannula 420 and the threaded coupling feature 412 of the pumphousing 410, but a ridge 419 is supplied as part of the coupling feature412. The inflow cannula 420 can be threaded into the coupling feature412 until one end of the inflow cannula 420 is positioned in the flowpassage 414 and seated in or against an opening of the rotor well 450.The threaded connection between the inflow cannula 420 and the couplingfeature 412 can be a single threaded connection. The threads of theinflow cannula 420 and the coupling feature 412 can be complementary soas to ensure a snug fit.

FIGS. 5A and 5B depict a blood pump 500 according to a fourth embodimenthaving a similar construction to that of the embodiments describedabove, but having a multi-component coupling feature 512. The couplingfeature includes a capture ring 516 and a rotating threaded component518 that mates with threads 525 in the inflow cannula 520. The capturering 516 secures the rotating threaded component 518 to the pump cap530, but allows for the rotating threaded component 518 to freelyrotate. The rotating threaded component thus prevents unintentionalunthreading of the threaded connection between the rotating threadedcomponent 518 and the inflow cannula 520. The rotating threadedcomponent 518 mitigates the risk of unthreading because torque on theinflow cannula 520 after connection will merely cause the rotatingthreaded component 518 to rotate with the inflow cannula 520. Therotating treaded component 518 and the capture ring 516 can be arrangedto mitigate the risk of opposing torque being placed on the rotatingthreaded component 518. The capture ring 516 can be welded to the pumpcap 530 or the pump housing 510. The capture ring 516 holds the rotatingthreaded component 518 against the remainder of the pump housing 510.The dimensions of the rotating threaded component 518 can prevent therotating threaded component 518 from becoming detached from theremainder of the pump housing 510, but dimensions of the rotatingthreaded component 518 and of the cavity between the pump housing 510and the capture ring 516 allow the rotating threaded component 518 tofreely rotate without excessive frictional or mechanical counteringforces. In some embodiments, the rotating threaded component 518 has acircular outer perimeter. The capture ring 516 can have a circular innersurface. The inflow cannula 520 can be threaded into the rotatingthreaded component until the end of the inflow cannula is seated in therotor well 550. The rotating threaded component 518 can include grooves519 to allow the rotating threaded component 518 to be held stationaryor be rotated during the threading of the inflow cannula 520 into therotating threaded component 518. Grooves 519 include one or moresurfaces that are generally in a plane including an axis of the threads.The axis of the threads is the axis about which the threads spiral.Surfaces that are in a plane including an axis of the threads can beengaged to control the rotation of the rotating threaded component 518to allow the inflow cannula 520 to be threaded into the rotatingthreaded component 518. In other embodiments, grooves 519 can bereplaced by notches or ridges also providing a good grippingarrangement. In some embodiments, a tool can be used to engage thegrooves 519 during threading (and unthreading) operations.

The end of the inflow cannula 520 shown in FIGS. 5A and 5B include flats527 to prevent auto-rotation of the inflow cannula. The flats 527 engagewith corresponding structures along the flow passage 514 of the pumphousing 510 to ensure that the inflow cannula 520 does not rotaterelative to the pump housing during use. In some embodiments, the flatsare part of a snap-fit connection that can be overcome with a torquegreater than a predetermined torque. For example, the predeterminedtorque can be set at a level greater than the torques normallyexperienced by a blood pump when implanted.

FIGS. 6A and 6B illustrate a blood pump 600 according to a fifthembodiment having a modified multi-component coupling feature 612including a capture ring 616, a threaded component 618, and an O-ring617. The O-ring 617 can be pressed between the capture ring 616 and thethreaded component 618 to mitigate the risk of blood and/or other fluidsleaking past the threaded connection. Threaded component 618 is adaptedto mate with threads 622 in the inflow cannula 620. The capture ring 616secures the threaded component to the pump cap 630. The capture ring 616can be welded to the pump cap 630 or the pump housing 610. The inflowcannula 620 can be threaded into the threaded component until the end ofthe inflow cannula is seated in the rotor well 650. The threadedcomponent can include keyways that mate with the capture ring 616 toprevent rotation during assembly. The keyways can include one or moresurfaces that are generally in a plane including an axis of the threads.Surfaces that are in a plane including an axis of the threads can beengaged to control the rotation of the threaded component 618 to allowthe inflow cannula 620 to be threaded into the threaded component 618.In other embodiments, keyways can be replaced by grooves, notches, orridges also providing a good gripping arrangement.

FIGS. 6A and 6B illustrate a ridge 629 having grooves 627 therein.Grooved ridge 629 can permit a tool to easily grasp the inflow cannula620 for installing the inflow cannula to the pump housing 610.Projections 619 can be formed on the threaded component 618 to allow thethreaded component 618 to be held stationary or be rotated during thethreading of the inflow cannula 620 into the threaded component 618.

FIG. 7 illustrates a blood pump 700 according to a sixth embodimenthaving an inflow cannula 720 having a flange 712 adapted to be welded tothe pump housing 710 or the pump cap 730. A welded connection canprovide a permanent attachment. In some embodiments, the inflow cannulacan be attached in a manufacturing facility. In other embodiments, theinflow cannula can be welded to the pump housing at the point of use bya clinician.

Textured Surfaces

One or more blood contacting surfaces of the blood pumps describedherein can include textured surfaces that may encourage or promote theformation and adherence of a biologic lining. The choice of whether toinclude a textured surface or a smooth surface on blood-contacting pumpcomponents may affect clinical outcomes. In some embodiments, a sinteredtitanium beaded surface is applied. The sintered titanium bead surfacecan be used to promote growth of a neointima layer, pseudo-neointimalayer, endothelial layer, or combination thereof. A biological layer(e.g. pseudo-neointima) formed on pump surfaces can act similar to abody surface to mitigate thrombus formation. Even in the absence of abiologic layer, the surface can be treated or modified in other ways soit becomes passivated. The lack of a textured surface may be desirablein some circumstances because it is easier to clean.

The textured surfaces may be made from a metal, such as a powderedmetal, or a polymer. For example, the textured surface may be a sinteredtitanium beaded surface. Textured surfaces and their fabrication areknown in the art and are used in a variety of medical applications. Forexample, U.S. Pat. No. 6,050,975 to Poirier, which is herebyincorporated by reference for all purposes, describes textured surfaces.The roughness of the textured surface can be measured by determining aRa value, which is the arithmetic average of the absolute amplitudevalues of the surface. In some embodiments, the Ra value of the texturedsurface is greater than 100 millionths of an inch, greater than 200millionths of an inch, or greater than 500 millionths of an inch. Insome embodiments, the textured surface has a Ra value of at least 200millionths of an inch, at least 500 millionths of an inch, or at least1000 millionths of an inch. In some embodiments, the textured surfacehas a Ra value of less than 10,000 millionths of an inch, less than5,000 millionths of an inch, less than 1,000 millionths of an inch, orless than 500 millionths of an inch. In some embodiments, the smoothsurfaces can have a Ra value of less than 100 millionths of an inch. Thepump cover may also include textured blood-contacting surfaces.

Textured surfaces, however, may be difficult to clean after exposure toan unsterile environment and/or wet environment. As discussed below,calibration of a blood pump includes operating the pump prior toimplantation using a calibration fluid. Because in some embodiments theinflow cannula includes textured surfaces exposed to the fluid, the pumpmay require a tedious and time-consuming cleaning process beforeimplantation. There may also be the risk that the surface does notbecome entirely clean and the pump will not be accurately calibratedwhen it is implanted. It may also be contaminated from the calibrationprocess.

FIG. 8A illustrates an example of a blood pump 824 having variouscomponents with textured surfaces that include a coating 870 ofmicrospheres. In various embodiments, the coating comprises sinteredtitanium microspheres. The blood pump 824 includes a housing 826 thatdoes not include textured surfaces that contact blood. The blood pump824 also includes an inflow cannula 830, a pump cover 840, and anoutflow adapter 850, each of which is removably attachable to the pumphousing 826 and includes one or more textured surfaces having thecoating 870. In FIG. 8A, the coating 870 is shown with a dotted patternand edges having the coating 870 are shown with darkened lines.

Because textured surfaces of the exemplary pump 824 are included on onlycomponents that are removable from the housing 826, the removablecomponents can be replaced with production equivalent components havingsmooth surfaces for the purposes of pump calibration. In this manner,surfaces with the coating 870 are not exposed to contamination duringcalibration. In the assembled blood pump 824, the majority of thesurfaces that contact blood have the coating 870, which limits thepotential for thrombus formation. Additionally, this configurationeliminates or reduces the need to clean the textured surfaces exposedduring the calibration process. Instead, the components can be replacedwith production equivalents without affecting the rest of the pumpsystem. By contrast, conventional pumps require disassembly of the pumpto replace similar components. Thus, the exposed components in aconventional setup cannot be replaced without requiring the need toperform another calibration process.

The housing 826 has an inner wall 827 that defines a rotor well 828. Arotor 829 is received in the rotor well 828 and rotates within the rotorwell 828 when the blood pump 824 is in use. The inner wall 827 thatdefines the rotor well 828 is located in the path of blood flow throughthe pump 824 and thus contacts blood. The inner wall 827 is smooth, forexample, the surface of the inner wall 827 does not have the coating870.

The rotor 829 has blades 862 that extend radially outward from an axisof rotation of the rotor 829. The rotor 829 also includes an innersurface 861 that defines a central opening 865 that permits blood flowthrough the rotor 829. The inner surface 861 is smooth, for example,without the coating 870. In some implementations, none of the surfacesof the pump housing 826 or the rotor 829 have textured surfaces, such aspowdered metal coatings. Because the pump housing 826 and the rotor 829do not have any powdered metal coatings on blood-contacting surfaces,the pump housing 826 and the rotor 829 may be easily cleaned after usein calibration of the blood pump 824.

As discussed further below with respect to FIGS. 8B-8F, in someimplementations, the coating 870 is deposited on most or allblood-contacting surfaces of the inflow cannula 830 and the pump cover840. As a result, a majority of the blood-contacting surfaces of thepump include the coating 870, even though the housing 826 may be free ofthe coating 870. For example, because the inflow cannula 830 extendsinto the pump housing 826, a surface having the coating 870 is locatedat a position within the housing 826 even though the coating 870 is notdeposited on the housing 826.

The blood pump 824 has an inlet 867, defined by the inflow cannula 830,and an outlet 868 defined by the pump cover 840. A blood flow path isdefined between the inlet 867 and the outlet 868. Surfaces with thecoating 870 occur along the entire blood flow path except in the rotorwell 828. For example, surfaces having the coating 870 can occur alongall regions of the blood flow path except in regions adjacent the rotor829, or adjacent blades 862 of the rotor 829.

FIGS. 8B and 8C illustrate the inflow cannula 830, which has an innersurface 831, a first outer surface 832 that extends outward from theblood pump 824, and a second outer surface 833 that is received withinthe blood pump 824. The coating 870 is deposited on at least a portionof the inner surface 831 and at least a portion of the first outersurface 832, which are blood contacting surfaces. The inflow cannula 830has a proximal edge 835 that may also include the coating 870, or maynot include the coating 870. In some implementations, a portion of theouter surface 832 may omit the coating 870 to avoid undesiredinteractions with myocardial tissue. In some implementations, all of thesurfaces of the inflow cannula 830 that are exposed to blood have thecoating 870. In some implementations, the coating 870 is not depositedon the second outer surface 833, which does not contact blood.

In some implementations, the coating 870 is applied to a proximal region837 of the interior surface 831, but the coating is not applied to adistal region 835 of the interior surface 831. The proximal region 837includes the portion of the inner surface 831 that extends from the pumphousing 826 in the assembled blood pump 824. The proximal region 837 mayalso extend into the pump housing 826, and may extend alongsubstantially all of a tapered portion of the inner surface 831. Thedistal region 836 can be a generally cylindrical region that is locatedadjacent the rotor well 828 in the assembled blood pump 824. In someimplementations, the distal region 836 is a region having the smallestinner diameter of the inflow cannula 830. The coating 870 may be omittedalong some or all of the distal region 836 to provide a transitionregion between, for example, the textured surface of the proximal region837 and a surface of the rotor well 828 having a different texture(e.g., a smooth surface).

FIGS. 8D to 8F illustrate various views of the pump cover 840. The pumpcover 840 has inner surfaces 842 that define a volute 844. The volute844 can define an expanding volume that converts kinetic energy of bloodflow to pressure at an outlet 868 of the blood pump 824. Some or all ofthe inner surfaces 842 have the coating 870. In some implementations,all of the surfaces of the pump cover 840 that are exposed to blood havethe coating 870.

Referring again to FIG. 8A, components other than the pump cover 840 andthe inflow cannula 830 can include surfaces with textured surfaces. Forexample, the outflow adapter 850, which attaches to the pump cover 840,includes the coating 870 on interior surfaces 852 that contact blood. Insome implementations, the outflow adapter 850 can be rotatably connectedto the pump cover 840. For example, a first end 854 of the outflowadapter 850 can be received within an outlet portion of the pump cover840 in a non-threaded manner. A fastener 856 can threadedly attach tothe exterior threads of the pump cover 840, capturing the first end 854.A second end 858 of the outflow adapter 850 can be attached to anoutflow graft 860 that returns blood to a patient's circulatory system.The engagement of the outflow adapter 850 to the pump cover 840 permitsthe outflow adapter 850, and thus the outflow graft 860, to rotate withrespect to the pump cover 840 and the pump 824 as a whole.

Calibration Procedure

A controller assembly and/or a controller in the pump housing 110 caninclude software that controls the operation of the pump and/orcalculates the flow rate of the implantable blood pump system while inservice. The controller assembly or the controller in the pump housingcan include a processor (e.g., a computer processor) that executesinstructions and/or outputs data. Clinicians can use flow rateinformation, along with other information, to determine the optimaloperational characteristics of the pump for each patient. Apre-implantation calibration of this software can be used to ensure thatthe flow rate calculations are accurate for each particular implantablemedical pump. Calibration can improve the accuracy of detectingventricular suction and/or other clinically relevant events.

FIG. 9 is a flow chart of an exemplary pre-implantation calibrationmethod for an implantable medical pump. In some implementations,components of the medical pump that have a textured surface, such as thecoating 870, are not used during calibration to avoid contamination. Forpurposes of calibration, clinical pump components having texturedsurfaces are replaced with different components, referred to ascalibration components, for use during calibration. The clinicalcomponents do not need to be cleaned after calibration because they aredetached from the pump and are not used during calibration. In someimplementations, where the pump components have textured surfaces, thecalibration components have surfaces with a different texture, forexample, smooth surfaces. In other implementations, the calibrationcomponents have surfaces with the same textures as the clinical pumpcomponents.

In the exemplary embodiment, the calibration components are generallyproduction equivalents of the clinical components. As used herein,“production equivalent” refers to components manufactured using the sameprocess, as would be understood by one of skill in the medical field,and in various respects, the field of medical device manufacturing. Verygenerally, the calibration components are manufactured to the samespecifications and are functionally equivalent to the clinicalcomponents. Thus, the calibration process does not need to be repeatedwhen the calibration components and clinical components are switched.The hydraulic operation of the pump is the same during calibration as inthe final clinical configuration of the pump. For example, the fluidpathway defined by a calibration cannula, a calibration cover, and thepump housing has the same geometry as the fluid pathway defined by theclinical inflow cannula, the clinical pump cover, and the pump housing.In addition, the particular motor and particular rotor used together forcalibration are shipped and implanted together. As a result, with thecalibration components attached to the housing, the flow geometrythrough the pump in the calibration assembly is the same as the flowgeometry through the pump in an assembly of the pump with clinicalcomponents.

For example, the portions of the calibration components that defineportions of a blood flow path within the medical pump can havesubstantially equal dimensions to the corresponding portions of clinicalcomponents. With the calibration components, the medical pump can haveperformance characteristics that are within a predetermined tolerance ofcharacteristics of the medical pump with clinical components used forimplantation. For example, performance of the medical pump with thecalibration components may deviate from the performance of the bloodpump with the clinical components by 20% or less, 10% or less, or 5% orless. Dimensions of the calibration components may be, for example, 10%or less or 5% or less of the dimensions of clinical components.

The calibration components can be production equivalents of the clinicalcomponents. In other words, the calibration components are manufacturedusing the same production procedures and under the same protocols usedto manufacture the clinical components. In some implementations, thecalibration components are manufactured to the same specifications asthe clinical components.

The method 900 includes coupling 910 a pump housing (including themotor) to a calibration cannula prior to operating the motor with thecalibration fluid. The calibration cannula can be reusable and used formultiple calibration processes with multiple pump housings. Thecalibration cannula can have dimensions equal to or approximating thatof an inflow cannula (such as those shown in the figures). For example,the calibration cannula can have the same features and dimensions of aninflow cannula for the pump, but with smooth surfaces instead oftextured surfaces. As an alternative, the calibration cannula can havetextured surfaces. For example, the calibration cannula can be a secondinflow cannula that is identical to the inflow cannula of the pump.

When a pump cover includes textured surfaces, the method 900 alsoincludes coupling 915 the pump housing to a calibration cover, which canhave dimensions equal to or approximating that of the pump cover. It ispossible that the difference between the calibration cover and the pumpcover is only a difference in surface texture, with the pump coverhaving a textured surface and the calibration cover having acorresponding surface that is smooth. Even in this case, theinaccuracies during the calibration process may still remain withinacceptable levels. As an alternative, the calibration cover may includetextured surface. For example, the calibration cover may be a secondpump cover that is identical to the pump cover.

In other embodiments, the calibration can occur when the pump housing isconnected to the pump cover. For example, in some embodiments, the pumpcover can be free of textured surfaces and thus mitigate the risk ofcontamination due to the calibration procedure.

After connecting the calibration cannula and the calibration cover tothe pump housing, the motor is operated 920 using a calibration fluid.Calibration variables are recorded 930. The calibration values can bebased on a flow, a pressure, a speed, an operational power, or acombination thereof of calibration fluid pumped by the blood pump.Recorded calibration variables are then imbedded 940 in the software ofa control system of the pump. For example, the calibration variables maybe stored in an internal memory of the pump. As another example, thecalibration variables may be stored in a memory of an implantablecontroller or an external controller. During operation of the pump, thevalues stored as calibration variables may be accessed and used tocontrol operation of the pump.

The pump housing (including the motor) is then detached 950 from thecalibration cannula. A calibration cover can also be detached 955.Exposed surfaces of the pump housing are then cleaned 960. Cleaning 960,for example, can include the use of soaps, detergents, water, organicsolvents, heat, pressure, and/or ultrasonic energy.

After cleaning, an inflow cannula can be secured 970 to an attachmentfeature of the pump housing. A pump cover can also be secured to thepump housing. In some embodiments, the inflow cannula and/or the pumpcover are secured to the pump housing prior to packaging. In otherembodiments, the inflow cannula and/or the pump cover are secured to thepump housing at the point of use by a clinician. In some embodiments,the calibrated blood pump is packaged 980 with one or more inflowcannulas. The packaging can further include tools adapted to secure theinflow cannula to the pump housing.

As noted above, the inflow cannula and/or the pump covering can havetextured surfaces. The textured surfaces may be difficult to cleanfollowing a calibration process. Accordingly, the above notedcalibration process results in a calibrated blood pump having texturedblood-contacting surfaces while avoiding a contamination risk of thetextured surfaces.

Each of the calibration components has features that correspond to thefeatures of the actual pump components. For example, the inflow cannulaand the calibration cannula each define a lumen. The pump cover and thecalibration cover each have an inner surface that defines a volute. Inregions where the pump cover and inflow cannula have textured surfaces,such as a powdered metal coating, the calibration cover and calibrationcannula have smooth surfaces.

The calibration components used during the calibration process canapproximate one or more of the dimensions of the actual pump components.To approximate a pump component, a calibration component may have one ormore dimensions substantially equal to the dimensions of the pumpcomponent. For example, the calibration component may have innerdimensions, or dimensions of blood-contacting surfaces, that are within20%, within 10%, or within 5% of the corresponding dimensions of thepump component. In some implementations, a calibration component isidentical to a pump component except for surface texture.

Referring to FIGS. 10A-10G, an inflow cannula can be attached to a pumphousing using one or more tools. For example, an inflow cannula 120 canbe attached to a pump housing 110 using a specialized socket 1000 and atorque wrench 1010. The torque wrench 1010 can be a torque-measuringwrench. For example, the torque wrench 1010 can include a gauge 1015that indicates the amount of torque being applied with the wrench 1010.Digital torque wrenches can also be used. The torque wrench 1010 can beused to ensure that the inflow cannula 120 is secured to the pumphousing 110 with a predetermined amount of torque. In some embodiments,the predetermined amount of torque is greater than 25 inch-pounds(in-lbf). In some embodiments, the predetermined amount of torque isbetween 25 and 150 in-lbf. In some embodiments, the torque wrench 1010is a torque-limiting wrench that limits an amount of torque applied withthe wrench to a predetermined amount.

The socket 1000 has a cylindrical inside surface 1028 having dimensionsthat correspond to the outside surface of the inflow cannula 120. Thesocket 1000 also includes grooves or projections that correspond tofeatures of the inflow cannula 120 so that the socket can be used toapply torque to the inflow cannula 120 about a central longitudinal axis1050 (illustrated in FIGS. 10E and 10F). FIGS. 10A-10G illustrate asocket 1000 having projections 1027 extending out from a rim of thesocket 1020 in a direction that is generally parallel with the centrallongitudinal axis 1050. In certain embodiments, the socket 1000 caninclude grooves or projections on an inside surface 1028 of the socketthat mate with corresponding features of an inflow cannula. A socket1000 and/or a torque wrench 1010 can be supplied with one or morecannulas and one or more blood pumps as part of a kit and/or soldseparately. In some embodiments not shown, the socket 1000 can beintegral with a torque wrench 1010. The torque wrench 1010 can beprogrammed to identify a predetermined amount of torque.

Referring to FIGS. 10G to 10M, the pump cover 160 can also be attachedto the pump housing 110 or adjusted relative to the pump housing 110.The pump 105 can include a capture ring 130 that has an inner diameterthat is smaller than an outer diameter of the pump cover 160. Thecapture ring 130 fits over a peripheral edge 140 of the pump cover 160,and when attached to the pump housing 110, the capture ring 130 capturesthe pump cover 160 against the pump housing 110. A sealing ring 162 canbe located between the pump cover 160 and the pump housing 110 to limitor prevent blood leakage.

The pump cover 160 engages the pump housing 110 with a non-threadedconnection. In some implementations, the pump cover 160 is rotatablerelative to the pump housing 110 while secured to the pump housing 110,for example, while the pump cover 160 is captured between the pumphousing 110 and the capture ring 130. When assembled, the pump cover 160and the capture ring 130 maintain the pump cover 160 in a fixedposition, due to friction and in some implementations, compressiveforce, unless at least a predetermined amount of torque is applied. Whensufficient torque is applied to the pump cover 160 relative to the pumphousing 110, the pump cover 160 may rotate in a direction shown by arrowA (FIG. 10I). In some implementations, the pump cover 160 rotatesrelative to the pump housing 110 about a central axis of the pump 105,such as a central longitudinal axis through the inflow conduit 120 or anaxis of rotation of a rotor.

In some implementations, a clinician first applies torque to loosen thecapture ring 130 from the pump housing 110, which permits the pump cover160 to rotate. When the outflow port 165 is in a desired orientation,the clinician tightens the capture ring 130 to restrict further rotationof the pump cover 160.

In some implementations, a clinician can rotate the pump cover 160 withrespect to the pump housing 110 without loosening the capture ring 130.The pump cover 160, pump housing 110, and capture ring 130 may bedimensioned to permit rotation of the pump cover 160 while the capturering 130 is fully secured to the pump housing 110. In someimplementations, to facilitate rotation, a coating or insert, such as apolytetrafluoroethylene ring, can be inserted between the pump cover 160and the capture ring 130 and/or between the pump cover 160 and the pumphousing 110. As a result, a clinician receiving the assembled blood pump105 may adjust the position of the outflow port 165 with respect to thepump housing 110 while the pump cover 160 is secured in an implantableconfiguration.

In some embodiments, the predetermined amount of torque required toloosen the capture ring 130 or rotate the pump cover 160 is greater than25 in-lbf. In some embodiments, the predetermined amount of torque isbetween 25 and 150 in-lbf.

As shown in FIGS. 10J and 10K, the capture ring 130 has interior threads132 that engage exterior threads 112 defined at an outer perimeter ofthe pump housing 110. The pump housing 110 also defines a generallycircumferential groove 113 that receives the peripheral edge 140 of thepump cover 160 (FIG. 10K). In the assembled pump 105, the peripheraledge 140 is located in the circumferential groove, and an annular wall134 of the capture ring 130 limits the pump cover 160 from separatingfrom the pump housing 110. Referring to FIG. 10L, a clinician can adjustthe position of the outflow port 165 using the torque wrench 1010 oranother tool. In the example shown, the torque wrench 1010 engages anadapter 1030 that has a socket 1020 complementary to an extension 1012of the torque wrench 1010. The adapter 1030 includes pins 1032 thatextend into holes 135 defined in the capture ring 130 to establish asecure connection between the adapter 1030 and the capture ring 130.While the pump housing 110 is held in a fixed position, the cliniciancan use the torque wrench 1010 to loosen the capture ring 130. With thecapture ring 130 loosened, the clinician can then rotate the pump cover160 relative to the pump housing 110. After the pump cover 160 is in adesired rotational orientation with respect to the pump housing 110, theclinician uses the torque wrench to tighten the capture ring 130, fixingthe rotational position of the pump cover 160.

In some implementations, the clinician removes the capture ring 130 fromthe pump housing 110 and replaces the pump cover 160 with a differentpump cover, for example, a pump cover with an outlet having a size ortrajectory different from the outflow port 165. The clinician thenreplaces the capture ring 130 to secure the new pump cover to the pumphousing 110.

In some implementations, as noted above, the clinician can rotate thepump cover 160 relative to the pump housing 110 without first looseningthe capture ring 130 from the motor housing.

Implanted System

FIG. 1C is a front view depicting an embodiment of an implantablemedical pump system 10 including a portable external controller 30 andtwo external batteries 40. In the embodiment depicted here, theimplanted medical pump system 10 includes an implantable medical pump100, an internal controller assembly 60 (that can include one or moreinternal batteries), and a percutaneous lead 70. The controller assembly60 can be implanted in, for example, the thorax, the abdomen, or anyother part of a patient's body as appropriate and can be electricallyconnected to the implantable medical pump 100 such that the controllerassembly 60 can control functions of and monitor the implantable medicalpump 100. As discussed below, the controller assembly 60 can includesoftware (e.g., machine-readable instructions that may be executed byone or more processors) and stored calibration values for calculatingflow rates and/or controlling the operation of the implantable medicalpump 100. In other embodiments (not shown), a controller storingsoftware and calibration values can be included within the pump housing110 rather than in a separate housing.

The use of the controllers 30, 60 between the pump 100 and the externalbatteries 40 is optional. For example, control of the pump 100 can beimplemented in the pump 100, and the external controller 30 andimplanted controller 60 may be omitted. As an alternative, thecontroller may be implemented entirely in the controller 30 or in theimplanted controller 60.

Power for normal operation of the system 10 can be supplied by theinternal batteries included in the controller assembly 60, within thepump housing 110, or by an external power source (such as the externalbatteries 40). The blood pump system 10 can be electrically coupled viathe percutaneous lead 70 to an external controller and/or power source.The percutaneous lead 70 can include a flexible outer housing enclosingredundant electrical lead sets, for example as discussed in U.S. patentapplication Ser. No. 12/472,812, filed May 27, 2009, which is herebyincorporated by reference for all purposes. Other systems includingblood pumps are also contemplated.

Referring back to FIGS. 1A and 1B, the implantable medical pump 100 canalso include an outflow port 165 for expelling blood that has been drawnby the implantable medical pump 100 from the interior chamber of theheart. As shown, the outflow port 165 can be located along the perimeterof the pump housing 110. In some embodiments, the outflow port 165 canbe part of a pump cover 160. The outflow port 165 can be fluidlyconnected via flexible conduit 167 (see FIG. 1C) to the aorta such thatblood drawn from the interior chamber of the heart can be expelled underpressure into the circulatory system of the user. As such, theimplantable medical pump 100 can augment the pumping of blood performedby the heart. The implantable medical pump 100 can also include afluid-tight bulkhead fitting 180 that allows an electrical conduit 185to pass from outside the implantable medical pump 100 into the interiorof the implantable medical pump 100, while maintaining a fluid-tightseal.

Pump housing 110 can define a passage containing a rotor that isactuated by elements at least partially contained within the pumphousing 110. For example, the pump housing 110 can include electricalcoils. Electrical power can be supplied to the push magnets embedded inthe rotor with an electromagnetic field. An example of the motor isdescribed in more detail in co-pending U.S. patent application Ser. No.13/212,813, filed Aug. 18, 2011, entitled “IMPLANTABLE BLOOD PUMP,”which is hereby incorporated by reference for all purposes.

A controller (either inside the pump housing 110 or exterior to the pumphousing) can control the delivery of electrical power supplied to thecoils to control the flow, speed, or pressure of blood pumped. The rotorcan contain hydrodynamic elements, e.g. blades, which functions as animpeller that, when rotating, can increase the pressure of fluid withinthe implantable medical pump 100. The passage can define a rotor wellcontaining the rotor. Blood can enter through the inflow cannula 120,pass into the rotor well, and be accelerated by the rotor in the rotorwell, causing the accelerated blood to flow radially outward and exitthrough the outflow port 165 where it continues through the flexibleconduit 167 and into the circulatory system. The depicted implantablemedical pump 100 is advantageously compact and, due in part to theoverall mushroom shape, can be readily secured to a heart wall.

FIG. 1B also illustrates an example of how an implantable medical pumpcan be secured to a heart. The implantable medical pump 100 (e.g., animplanted centrifugal blood pump) can be secured to a heart 20 using amounting cuff 102 and medical sutures 104 such that an inflow cannula120 traverses a myocardium of the heart 20.

Implantation Procedure

The blood pump can be implanted in the wall of the left ventricle, e.g.,near the apex of the heart. In other embodiments, the implantablemedical pump 100 is implanted in the wall of the right ventricle. Inother embodiments, the blood pump is attached to an atrium, e.g. if aleft ventricle has been resected. The selected implantation site canimpact the selected inflow cannula given the variations in myocardialwall thicknesses and shapes, and the desired inflow cannula flowtrajectories.

A scalpel and/or a coring knife can be used to incise a cylindricalopening through the apex into the left ventricle approximately thediameter of the exterior end of the inflow cannula. When the opening hasbeen incised, the inflow cannula can be advanced into the opening untilthe pump housing 210 contacts the heart wall. The blood pump can then besecured in place using sutures and a mounting cuff. The mounting cuffcan be attached to the blood pump and/or the myocardium by threads,detents, a series of sutures, a series of snaps, a band or strap, afriction fit, and the like.

A number of embodiments have been described. Nevertheless, it will beunderstood that various modifications may be made without departing fromthe spirit and scope of this document. Accordingly, other embodimentsare within the scope of the following claims.

What is claimed is:
 1. An implantable medical pump system, comprising: acentrifugal blood pump comprising a pump housing defining a passagetherethrough and a rotor within the passage, the pump housing at leastpartially containing one or more elements configured to actuate therotor to drive fluid through the passage, the pump housing comprising atleast one coupling feature; and a plurality of differing inflowcannulas, each inflow cannula of the plurality defining a lumentherethrough and being configured for alternate modular attachment tothe at least one coupling feature.
 2. The system of claim 1, wherein atleast one inflow cannula of the plurality comprises a texturedblood-contacting surface, and wherein at least a portion of each inflowcannula of the plurality extends into the passage when the inflowcannula is attached to the at least one coupling feature.
 3. The systemof claim 2, wherein the textured blood-contacting surface comprisessintered titanium powder.
 4. The system of claim 1, whereinsubstantially all of the blood-contacting surfaces of the at least oneinflow cannula include a textured coating.
 5. The system of claim 1,wherein each inflow cannula of the plurality is configured to extend outfrom the pump housing when coupled to the at least one coupling featuresuch that a portion of each inflow cannula of the plurality isconfigured to traverse an myocardium of a heart.
 6. The system of claim1, wherein the inflow cannula comprises: a first portion having a lengthsufficient to traverse a heart wall, the lumen extending through thefirst portion; an exterior thread pattern to mate with an interiorthread pattern of the blood pump, the first portion protruding from theblood pump when the exterior thread pattern engages the interior threadpattern of the blood pump; and a second portion having a generallycylindrical outer surface received inside the passage of the blood pumpwhen the exterior thread pattern engages the interior thread pattern ofthe blood pump, the second portion having a smaller outer diameter thanthe first portion.
 7. The system of claim 1, wherein the inflow cannulais configured to extend along at least 50% of the length of the passagewhen mechanically coupled to the at least one coupling feature to arotor well defined by the passage.
 8. The system of claim 1, wherein thepassage defines a rotor well that receives the rotor, wherein the inflowcannula is configured to extend to the rotor well when mechanicallycoupled to the at least one coupling feature.
 9. The system of claim 1,wherein the system comprises multiple inflow cannulas each configured tobe reversibly mechanically coupled to the at least one coupling featuresuch that at least a portion of the flow cannula extends into thepassage, at least two of the inflow cannulas having different lengths.10. The system of claim 9, wherein at least a first inflow cannula isconfigured for traversing the myocardium of a left ventricle and asecond inflow cannula is configured for traversing the myocardium of aright ventricle.
 11. The system of claim 1, further comprising a pumpcover that is removably attachable to the pump housing, the pump coverdefining a volute and comprising a textured blood-contacting surface.12. The system of claim 1, wherein the centrifugal blood pump isconfigured to mount to or directly adjacent to a wall of the heart suchthat the inflow cannula traverses the heart wall when the system isimplanted.
 13. The system of claim 1, further comprising: a wrenchsystem including a torque-limiting or torque-measuring wrench tofacilitate secure attachment of a selected inflow cannula of theplurality with a predetermined amount of torque.
 14. An implantablemedical pump system, comprising: a centrifugal pump housing defining apassage therethrough and a rotor at least partially disposed in thepassage in a rotor well, the pump housing at least partially containingone or more elements configured to actuate the rotor to drive fluidthrough the passage; and an inflow cannula that is removably attachableto the pump housing by at least one coupling feature of the housing, theinflow cannula having a lumen defined through the inflow cannula thatextends to the rotor well when the inflow cannula is attached to thepump housing by the at the least one coupling feature, the inner surfaceof the lumen having a textured blood-contacting surface.
 15. Theimplantable medical pump system of claim 14, wherein the lumen of eachinflow cannula of the plurality extends into the passage beyond the atleast one coupling feature when the inflow cannula is attached to thepump housing.
 16. The implantable medical pump system of claim 14,wherein the textured blood-contacting surfaces comprise a powdered metalcoating, and the pump housing does not have any blood-contactingsurfaces that comprise a powdered metal coating.
 17. The implantablemedical pump system of claim 16, wherein the powdered metal coatingcomprises a sintered titanium powder.
 18. The implantable medical pumpsystem of claim 14, a pump cover removably attachable to the pumphousing, the pump cover having an inner surface that defines a volute,the inner surface of the pump cover having a textured blood-contactingsurface, wherein the inflow cannula, the pump housing, and the pumpcover define a blood flow path through the pump, and the pump housingdefines a rotor well that receives a portion of the rotor, whereintextured blood-contacting surfaces are disposed along the entire bloodflow path except the rotor well.
 19. An implantable medical pump system,comprising: a blood pump comprising a pump housing defining a passagetherethrough and a rotor within the passage, the pump housing at leastpartially containing one or more elements configured to actuate therotor to drive fluid through the passage, the pump housing comprising atleast one coupling feature; a first inflow cannula defining a lumentherethrough and configured to be reversibly attached to the at leastone coupling feature, wherein the first inflow cannula comprises a firstregion along the lumen having a textured blood-contacting surface; and asecond inflow cannula defining a lumen therethrough having asubstantially equivalent flow geometry as the lumen of the first inflowcannula, wherein the second inflow cannula comprises a smooth surface ina second region corresponding to the first region.
 20. The implantablemedical pump system of claim 12, wherein each of the first and secondinflow cannulas is configured to extend into the passage of the pumphousing to a rotor well defined by the passage when mechanically coupledto the at least one coupling feature, and the textured blood-contactingsurface of the first inflow cannula is disposed along the entire bloodflow path to the rotor well.